This project represents phase II of a project whose main objective is to develop a non-invasive, safe, relatively inexpensive and accurate technique for the prenatal diagnosis of genetic disorders that can be performed during the first trimester. Phase II will test, expand and refine the methodology developed in phase I. The study will include a systematic evaluation of the variables involved in separating and enriching fetal cells from maternal blood through flow cytometry or other methods, including magnetic-activated cell sorting (MACS), followed by in situ hybridization with chromosome-specific DNA probes. The results of these peripheral blood studies will be compared to those that will be obtained from amniocentesis or chorionic villus sampling (CVS) on the same women. Another objective of the project is to determine whether or not there are any non-biological effects on the women undergoing prenatal diagnostic testing. Even if the biologic risks associated with reproductive genetic technologies are reduced, the possibility exists that other potential risks (or benefits) are associated with the procedures. Some of these factors may be: expanded or diminished maternal anxiety, increased adjustment or maladaptation to the pregnancy, increased feelings Of coercion to undertake prenatal testing when there are negligible biologic risks associated with the procedure, and increased or decreased comfort with reproductive decision-making.